Yet another immersion thread

soups05 · 15-04-2022 6:09pm #1

Hi guys, I have been reading a lot of threads regarding immersion heater wiring and mostly the advice is the same. my problem in slightly different. I have an external immersion, a willis heater, which came with a cable attached. This cable has three wires, brown, blue and green/yellow. identical to a standard t+e wire in every other household item.

I am trying to connect it to a double switch on/off one side, sink/bath on the other. All threads say it should have a fourth wire which should be paired for the sink bath side.

So how do I wire a three core immersion with the dual switch?

Bruthal. · 15-04-2022 7:13pm

If you are going to use an immersion switch, you can wire it direct through the 2 pole switch side if it is one of the switches where you add in the link. So supply into 2 pole, and immersion heater L & N out other side of the 2 pole.

So the 2 pole switch switches on and off the heater. And dont bother with the link to the 2 way bath sink side.

If it is the type of swirch with the link internal, just wire the brown to the bath terminal, and leave the switch on bath, and

use the on/off 2 pole side to switch on and off the heater.

John.G · 15-04-2022 8:04pm

And ensure the the correct way is "upside down" like shown.

John.G · 16-04-2022 12:36pm

https://www.boards.ie/discussion/2058241888/yet-another-immersion-thread

If you don't mind can you post a photo of your installation which I assume is working correctly in that it is providing hot water in 5 minutes or so but isn't switching the heating element on/off too often.

The Continental Op · 16-04-2022 1:04pm

Basically a Willis heater doesn't have two elements so you can only switch it on and off. There is no sink/bath option.

If you are out to save money best thing to do would be to install a timer switch one that gives you the ability to switch the immersion on for say 1/2, and hour or 2 hours. 1/2 would be fine for the sink and 2 hours probably OK for a full bath but without knowing the cylinder size you'd just have to try it. Something like this https://www.amazon.co.uk/Timeguard-TGBT4-Electronic-Boost-Timer/dp/B006SYK8U4/

John.G · 16-04-2022 1:17pm

One of its advantages? is that it heats the water from the top down so hot water should be available pretty fast, the temperature rise through the heater is dependent on the element power and convection so proper installation is vital but yes if you need only small volumes of hot water then a timer is the answer otherwise it will keep heating until almost the whole cylinder is hot and the thermostat then switches out the element. The trick is to get the circulation just right so that it gives water at 45/55C even from cold.

kirk. · 16-04-2022 7:12pm

https://www.boards.ie/discussion/comment/118934983#Comment_118934983

I wired a good few of them I think the plumber used to call them an "economiser"

Dunno was that a brand name or generic name if I'm thinking of the same heater

soups05 · 17-04-2022 6:12pm

https://www.boards.ie/discussion/comment/118934926#Comment_118934926

interesting. It has been installed in this house since i bought it, always had the old double switch So I guess i just assumed bath/sink were different options.

will try to get pics later. So far my tests are as follows:

top there are three options, com 1 and 2. i have the supply wired into 1 and 2 live and neutral respectively.

at the bottom are four options L1 and L2 on the bath sink side and 1 and 2 on the double pole on off side.

connecting L1 to load live and 2 to load neutral gives nothing. connecting L1 to load live and com to supply 1 gives no power when off but gives power (neon on) and water is heated. However this trips the rcd after 20 mins. the longest i have made it work is by connecting L1 to load live, L2 to 2 on the on off side and com to 1 on the load side. still trips after about three hours.

originally i tried to get a sparky to do this but he was a friend of a work colleague. popped in randomly on and off for months then ghosted. colleague had moved on too so no way to contact him. it was a weird set up from the start. Gas boiler, immersion and sons room all running through the same switch. he made many efforts and excuses but never got it working right.

i separated the gas/ sons supply into a junction box so it works even without the immersion but at this point its just a matter of pride to solve it. no sparky wants to call out cos job is too small compared to working a job site etc.

The Continental Op · 17-04-2022 7:37pm

John.G has given you the main info on this. Its a system for heating the water in a tank from the top down, so you don't waste money heating water you aren't going to use. If you get the timing right you can heat just enough water to wash dishes or have a quick shower when a traditional element would only give you a tank of lukewarm water for the same cost.

I've looked at them several times and might install one one day with a low voltage element in it so it can be powered directly by spare solar PV. The problem for that instal is that the adapter needed to change the element costs more than the whole unit.

Most of the information I've read says they are popular in Northern Ireland but I've nothing to prove that. I checked in the local Heat Merchants and no one could ever remember selling one although they managed to find a couple on the top of a shelf when one guy realised what I was asking about.

soups05 · 17-04-2022 8:37pm

Continental, yes John.G has given me very useful info. I understand the money saving aspect, i was just surprised that there was only one element. I am just swapping like for like and trying to wire the switch correctly without the benefit of knowing how it was wired originally. I have a few other tests to try but I am limited by the need to not trip the rcd while son is playing online or wife is watching soaps lol. UK diy sites appear to be under the impression that its a typical Irish setup which they do not use over there. meanwhile no one i spoke to has ever seen one over here. I would dearly like to get my hands on whoever installed this mess. There is a certain gas installer in Dundalk who will never get my business again for a start :-P

If I ever get it to work properly I will update of course. Hopefully tomorrow I may be able to post pics

Bruthal. · 18-04-2022 8:28am

As already said, as it looks like seperate non internal linked immersion switch, connect it using only the on/off side. L and N supply in and connect the brown and blue of element to load terminals on the other side of on/off switch.

No need to use the bath/sink switch terminals. If the element itself has any problems then obvious connecting correctly won't fix those.

soups05 · 18-04-2022 11:40am

Finally sorted (fingers crossed) Now that I understand there is only one element I went back to Bruthal's advice "supply into 2 pole, and immersion heater L & N out other side of the 2 pole." Completely ignored the bath/sink side and just used it as an on/off switch. It works perfectly and no trips so far.

My confusion arose from A) assuming all immersions had dual elements, B) the dual switch that was already there and C) that image in post three which always comes up for a willis heater. I thought it showed two elements on the right hand side.

See this is why I never mess with plumbing or electrics beyond wiring a plug lol. I am lucky I get through life on my good looks and charm not my brains. (I wish).

Thank you all for the advice and help. Sorry it took so long for me to grasp it.

John.G · 18-04-2022 12:57pm

Post 3 shows a single element, the piece in the center is the thermostat pocket.

Don't forget the earth wire.

John.G · 18-04-2022 12:58pm

soups05 · 18-04-2022 1:12pm

thermostat pocket.....ah, that explains it lol. God love me am just not that bright :)

John.G · 18-04-2022 2:43pm

Does the outlet from the immersion feel very hot or medium hot or whatever when on?. I'd be very interested in the temperature rise through the immersion because if too high then the thermostat will be cycling on/off which you will hear.

Yet another immersion thread

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